1. Field of the Invention
The present invention relates to guides for cutting torches and, more particularly, to an assembly for cutting circular holes in steel pipes and plates and for positioning a mating fitting.
2. Description of Related Art
In the normal course of welding an assembly of pipes there exists a requirement to cut a round hole of a specific size and at a specific location in one of the pipes. Subsequently, a further pipe is mated with and welded to the cut hole. In some instances, a fitting, sold under the trademark xe2x80x9cWELD-O-LETxe2x80x9d, is welded to the cut hole to provide threaded engagement for a threaded pipe to be attached to the fitting and associated pipe.
When the initial hole is cut freehand, circularity of the hole is often compromised but compensated for by the subsequent welding operation. When a WELD-O-LET fitting is to be attached, concentricity of the fitting with the hole is often compromised. Such lack of accuracy results in unnecessary flow restriction and pressure increase of the fluid flowing therethrough. This may result in a reduced flow rate or a requirement for a more powerful pump to cause fluid flow of an adequate volumetric rate.
An angularly offset pointer is positionally supported by a holder attached to the cylindrical portion of a conventional cutting torch tip. By angular rotational positioning of the pointer relative to its holder, the distance between the pointer and the cutting torch flame is set to define the radius of the hole to be cut. By placing the pointer in a dimple defining the center of the hole to be cut, the cutting torch is rotated about the pointer to accurately cut the hole to be formed in a steel pipe or sheet. A positioning fixture is magnetically attached to the pipe and magnetically supports a WELD-O-LET fitting at the cut hole to permit accurate tack welding of the WELD-O-LET fitting to the pipe. Thereafter, the positioning fixture is disengaged from the pipe and the WELD-O-LET fitting to permit final welding of the WELD-O-LET fitting to the pipe.
It is therefore a primary object of the present invention to provide an assembly for cutting a circular hole and for positioning a fitting to be attached thereto.
Another object of the present invention is to provide a guide for accurately cutting circular holes in a pipe or a sheet.
Yet another object of the present invention is to provide an adjustable guide for setting the radius of a circular cut to be made with a cutting torch.
Still another object of the present invention is to provide a hole cutting guide detachably attached to the tip of a cutting torch.
A further object of the present invention is to provide a magnetically attached fixture for magnetically positioning a fitting in concentricity with a cut hole.
A still further object of the present invention is to provide an assembly having a guide for accurately cutting a circular hole in a steel pipe or plate and a magnetically attached fixture for magnetically retaining a fitting to be welded in the cut hole.
A still further object of the present invention is to provide an inexpensive assembly for providing a guide to cut an accurate circular hole with a cutting torch and a fixture for accurately positioning a fitting concentric with the cut hole.
A still further object of the present invention is to provide a method for guiding the cutting of a hole in a steel pipe or plate and for magnetically attaching a fixture to locate a fitting in concentricity with the cut hole.
These and other objects of the present invention will become apparent to those skilled in the art as the description there proceeds.